1. Field of the Invention
The present invention relates to a system for measuring a viscosity of a gelable liquid in the fields of chemistry, physical chemistry, biochemistry, foodstuffs, medical services and the chemical industry. The viscosity measuring system utilizes a piezoelectric resonator for monitoring a viscosity change of a gelable liquid.
2. Description of Prior art
A capillary method, a rotational method, a falling ball method, and the like, have primarily been employed conventionally to measure a viscosity. The capillary method measures the viscosity of a liquid sample from its falling speed in a capillary and the falling ball method places a metal ball into a liquid sample and determines the viscosity from its falling speed. The rotational method rotates a cylindrical metal rod inside the sample liquid and determines the viscosity by measuring its shear stress.
The conventional viscosity measuring methods involve the problem that measurement is not possible for a limited amount of a sample. The capillary method and the falling ball methods are not free from the problem that a long measuring time and a great deal of labor are necessary for the measurement. Since the measurement is carried out by a mechanical system in accordance with the rotational method, this method involves the problems that the measurement is likely to be affected by external influences such as of vibration and maintenance of devices is also necessary.
Furthermore, in order to measure a gelation reaction, particularly a gelation reaction in the analysis of a blood coagulation system, a method which measures optically turbidity of a sample and a method which applies mechanical vibration and detects a viscoelastic change due to gelation have been employed conventionally.
The conventional method which measures turbidity involves the drawbacks that measurement of a colored sample cannot be made and since an optical measuring system is included, its system construction becomes complicated. On the other hand, the optical method is not said to be a correct method because it does not directly measure gelation. The method which applies mechanical vibration is not free from the problems that occur due to the presence of mechanical portions also, the system becomes complicated and trouble is likely to occur. The gelation reaction is likely to be impeded by mechanical vibration and there is a limit to the accuracy measurement by this method. In addition to these problems, all of the methods described above involve in common the problem that at least about 0.2 ml of sample is necessary.
Moreover, a viscosity measuring method by use of a torsionally vibrating crystal has also been developed.
In the case of the measuring method using the torsionally vibrating crystal, a certain amount of sample is necessary and the viscosity cannot be measured in an electrolytic solution.
Furthermore, no reports have been known in the past about the measurement of the viscosity change by use of a crystal.